Artificial cardiac pacemakers are typically calibrated after implantation and then re-calibrated periodically, such as every six months. Typically, a threshold voltage is determined by which, at a certain minimum voltage, the heart muscle is stimulated to contract, and then the artificial pacemaker is set at a voltage of about twice the threshold voltage. On the one hand, it is important for the inserted pacemaker to cause the heart to beat with regularity. On the other hand, since the pacemaker is battery-powered, with a limited battery life, and an electrical stimulus is being provided to the heart, the voltage should not be too high. The threshold voltage is defined as the minimum voltage needed to cause the heart to beat.
To detect a heart beat and measure the heart rate, the present method used, such as with threshold testing of an artificial pacemaker, is to use an EKG machine (electrocardiogram). The drawbacks to EKG's are the inconvenience to the patient in undressing and the time needed for preparation and carrying out the measurements. For example, patients are usually instructed to remove their jewelry. Men are instructed to remove their shirts. Women are often stripped down to a bra. The patient then lies on a bed or table while electrodes are attached, sometimes after shaving the patient. The electrode must be soaked in alcohol to improve conductivity in many cases. The patient must lie still and breathe slowly or hold his/her breath. The electrodes feel cold and stick to the skin.
What is needed in the art is a way to conduct pacemaker threshold testing without the patient having to undress, and, in some cases, to be shaved, as well as having electrodes attached.